Reactance tube circuit



May 3, 1949.

J. LJDELVAUX REAQTANCE TUBE CIRCUIT Filed July 16, 1947 -QIIIIIIW In\ /en tor" Jean LDeI vaux,

H is Attorney.

Patented May 3, 1949 REACTANCE TUBE omcurr Jean L. Delvaux, Paris, France, assignor to General Electric Company, a corporation of New York Application July 16, 1947, Serial No. 761,326 In France December 12, 1942 Section 1, Public Law 690, August 8, 1946 Patent expires December 12, 1962 Claims.

iii

fectively over a wide range of frequencies; and

a further object is to provide a reactance tube circuit so arranged that departures of the reactance tube current from a quadrature relationship with the voltage of an associated oscillator are minimized.

An additional object of the invention is to provide a reactance tube circuit particularly adapted for use with an oscillator of the three terminal type, wherein two alternating voltages of opposite phase are produced between two extreme or opposite terminals, respectively, and a third common or nodal terminal or point.

The novel features which I believe to be characteristic of my invention are set forth with particularity in th appended claims. My invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof may best be understood by reference to the following description taken in connection with the accompanying drawing in which Fig. 1 is a diagram of I a reactance tube circuit in association with an oscillator and Fig. 2 is a diagram showing a modification of the reactance tube circuit.

With reference to Fig. 1 of the drawings, an oscillator is shown comprising an electron discharge device I connected with a tapped induct-' ance 2 and capacitor 3 in a Hartley oscillator circuit, control electrode connection to the tank circuit, formed by inductance 2 and capacitor 3,,

being through a capacitor 4, and the cathode conis the same as the ground connection shown in the drawings. Each of terminals I and 8, ac-- cordingly, carries an alternating voltage with respect to the grounded intermediate point or terminal 9, and these two voltages are of opposite phase, though not necessarily of equal magnitudes.

Connected to terminals 1 and 8 is a reactance tube circuit comprising an electron discharge device III with its cathode connected to the nodal point, as represented by tap 9 or by ground, and with its anode connected to terminal I. The control electrode II is directly connected to an intermediate point represented by the interconnection of resistors I2 and I3 in a voltage dividing network. This network includes low impedance direct current blocking capacitors I4 and I5 and is arranged to furnish to control electrode II a fractional portion of the alternating voltage existing on terminal 8. Added to this fractional voltage by a capacitor I6 is a phase shifted voltage derived from terminal 'I. The

voltage applied by capacitor I6 to the control I electrode is nearly in quadrature with the voltage at terminal 'I, and added to this phase shifted voltage is a voltage from the voltage divider network IZ, I3 which is degrees out of phase with the anode voltage from terminal I. These two voltages provide a compensated or corrected control electrode voltage such that the reactance tube anode current is maintained with a minimum departure from quadrature with respect to the oscillator voltages.

The anode current, i of an electron discharge device, such as triode tube I0, is related to vthe alternating component of the anode voltage, e the alternating control electrode voltage, e and the anode resistance of the device, Tp, if the amplification factor of the tube is in accordance with the equation:

The voltage applied to the control electrode I I through the voltage dividing network I2, I3 is in phase opposition to 8p and may be proportioned, by adjustment of the value of resistor .'or otherwise, to be such that ueq= e The in-phase anode current of the tube due to the alternating anode voltage component would be thus overcome by the provision of this voltage from terminal 8 through the volta e divider.

In' addition, however. it will be found that the control electrode voltage supplied from terminal 1 through the phase shifting network I6, I3 is not exactly in quadrature with the voltage on terminal I but contains a small component in opposite phase.

where e, is the in-phase component of the voltage developed in the phase shifting network across resistor I3 by current from terminal I through capacitor I6.

Some small further corrections may be neces- .7

sary to compensate for inherent circuit capac-- itances, including interelectrode capacitances of. I

The inherent capacitance existing device |0. across resistorl2 is represented in Fig. 1 by the condenser l1 shown, in dotted lines.

It may be found convenient to provide a variable capacitor as capacitor l6, as well as a variable resistor as resistor I2, as they are both shown in Fig. 1, to permit any necessary adjustments to be made. be made adjustable instead of, or in addition to those mentioned, if desired, or the proper values of fixed elements may be utilized throughout.

A terminal I8 is shown connected to that end of resistor l3 which is connected to capacitor l5. A suitable biasing potential may be applied in any known manner to this terminal, and a modulating voltage, as for instance an audio voltage, may also be applied to alter the conductance of the tube III in a known 'manner. Capacitor l5 should be of low impedance at the frequency of the oscillator, but of high impedance at the frequency of modulating voltages applied to ter minal l8. i

In operation it will be found that the anode current of reactance tube III will not depart by more than a small angle from a quadrature relationship with the voltage of terminal I over a relatively wide range of frequencies generated by oscillator tube I.

It will be apparent to those skilled in the art that the voltages applied to the phase shifting network or to the voltage dividing network may be taken from other taps along inductance 2, or from a voltage dividing capacitance network replacing capacitor 3, as may be best suited to a particular situation, and other similar alternatives or modifications will be apparent to those skilled in the art.

In the modification of Fig. 2, is shown a tickler feedback, tuned grid type oscillator comprising discharge device I, grid tank inductance 2 and capacitor 3, and inductance i9 inductively coupled to inductance 2. oscillators are well known. Grid coupling capacitor 4 and grid leak resistor 6 perform well known Other suitable elements may, of course.-

' energize control electrode ll.

capacitors 23 and 24 conected in series to ground or, to any desired point at the alternating voltage node. The control electrode ll of electron discharge device 10 receives from its connection with the juncture of these two capacitors a fraction of the voltage of terminal 22 without substantial phase shift.

A voltage component is derived from the voltage on terminal 2| shifted in phase by nearly 90 degrees which appears at the juncture between a resistor 25, which is preferably variable as shown, and capacitor 24 connected in series from terminal 2| to ground to form a phase shifting network. A low impedance direct current blocking capacitor 26 is included to complete the circuit from terminal 2| to ground while preventing the B+ potential from reaching control electrode H.

The twovoltage components, from the voltage divider comprising capacitors 23 and 24, and from 25 and capacitor 24, are algebraically added to merit of these two voltages is in accordance-with the principles discussed in connection with Fig. 1.

'That is, the voltage providedfrom terminal 2| is shifted in phase by nearly 90 degrees at the point of connection of the control electrode II to the phase shift network 25, 24. The correcting voltage derived from. voltage divider network 23, 24

' 2| which is applied to the control electrode. In.

operation, as discussed above in connection with Fig. 1, the circuit of Fig. 2 provides an anodecurrent in reactance tube Ill differing from a quadrature relationship with the oscillator voltage, at terminal 2|, by not more than a small angle throughout a relatively wide frequency band. The'relationship may be made to be exactly quadrature at one frequency, and it will then be very nearly exactly quadrature for a substantial deviation from this frequency.

. ing functions described above, or'that in-phase power will be absorbed by the tube if the compensating voltage is reduced below the value necessary for full compensation. The quadrature component, of course, may be thought of as being a current drawn from or supplied tothe oscillator.

' Since it is in quadrature, it represents no power The operating principles of such functions, and capacitor 5 serves to ground for alternating current voltages the juncture 20 of windings 2 and 19. These two windings may be, if desired, separated by a capacitor or the like for direct current voltages, but interconnected for alternating currents. tential is provided by a suitable source, such as the battery shown connected to. supply B+ potential to the anode circuits of the discharge devices employed,

The oscillator of Fig. 2 provides voltages on terminals 2! and 22 with respect to juncture 20, grounded for alternating voltages, which are of The voltage on terminal 22 is applied to a voltage divider network comprising Positive operating pO- transfer between the oscillator and the reactance tube circuit. a

It may be found convenient to furnish variable elements to perform the functions of resistor 25 and capacitor 23, respectively, both as shown in Fig. 2, or to provide such other adjustable elements as are desired to furnish the flexibility for adjusting the circuit for different conditions. Elements of fixed values, however, are desirable if cost is important and if operation is to be within relatively narrow frequency limits.

' Terminal I8 is provided as a point for connecting through a suitable resistor 21 a biasing potential and, if desired, a modulating voltage, as

, heretofore explained in connection with Fig. 1.

The proportion-.

. 5 skilled in the art and I therefore wish to have it understood that I intend, in the appended claims, to cover all such modifications as fall within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A reactance tube modulator comprising means for generating two voltages of opposed phase with a common predetermined nodal point, an electron discharge device with an anode, a cathode connected for alternating voltages to said point, and a control electrode, means for applying one of said voltages to said anode, means for applying a voltage substantially in quadrature with said one voltage to said control electrode, means for deriving from the other of said two voltages a correcting voltage and for applying said correcting voltage to said control electrode whereby conduction of ln-phase anode current by said discharge device is minimized, and means for applying a modulating voltage to control the intensity of current conducted by said device.

1 2. A reactance tube circuit, adapted for use with a generator providing two alternating voltages of opposite phase with respect to a predetermined nodal point-on two respectively opposite terminals, said circuit comprising an electron discharge device with an anode connected for alternating current to one of said terminals, a control electrode, and a cathode connected for alternating current tosaid nodal point, a phase shift network for providing a control voltage to said control electrode which is nearly in quadrature with the voltage of said one terminal, and a voltage dividing network for applying a voltage derived from and in phase with the voltage of said other terminal to compensate for the deviation from quadrature of said control voltage and to compensate for the in-phase conduction of said device in response to the alternating voltage of said one terminal.

3. A frequency modulated wave generator comprising an oscillator anda'reactance tube; said reactance tube having a control electrode con nected to receive a voltage nearly in quadrature with a first voltage developed in said oscillator, an anode connected to conduct a reactive current which traverses a frequency controlling element of said oscillator, and a cathode; said generator being characterized by means associated with said file of this patent:

oscillator for developing a second voltage in phase opposition to said first voltage, and means for applying a predetermined fraction of said second voltage to said control electrode to minimize the in-phase component of said current.

4. A reactance tube circuit, for cooperation with an oscillator arranged to generate two alternating current voltages with respect to a predetermined reference point which are of the same frequency but of opposite phase at two oscillator terminals, said circuit including an electron discharge device with an anode, a cathode and a control electrode, a phase shift network comprising a reactance element and a resistance element for providing to said control electrode a voltage component approximately in quadrature with said two voltages, and a voltage divider network arranged to furnish a predetermined fraction of one of said voltages without phase shift to said control electrode whereby components of anode current in said device in phase with either of said two oscillator voltages are minimized.

5. In a frequency modulated wave generator comprising an oscillator for providing an alternating voltage between each of two respective terminals and an intermediate terminal, said voltages being in phase opposition at said two terminals; a reactance tube with an anode arranged to conduct reactive current from said osci1lator,

a control electrode connected to a phase shifting network arranged to supply thereto from a predetermined one of said two terminals a voltage nearly in quadrature with said alternating voltages, and a cathode connected to said intermediate terminal; a phase correcting network for.

said reactance tube comprising means for applying a voltage derived without phase shift from the voltage on the other of said two terminals to minimize the effect of departure from quadrature of said control electrode voltage. v JEAN L. DELVAUX.

. REFERENCES CITED The following references UNITED STATES PATENTS Date are of record in Crosby July 1a, 194: 

